Lupus nephritis

Alternative names:

lupus glomerular disease; nephritis - lupus

Definition:

A kidney disorder that is a complication of systemic lupus erythematosus, characterized by damage to the glomerulus and progressive loss of kidney function.

Causes, incidence, and risk factors:

Lupus nephritis is one complication of systemic lupus erythematosus (SLE). The exact mechanism by which lupus causes kidney damage is unknown. It is related to the autoimmune process of lupus, where the immune system produces antibodies (antinuclear antibody and others) against body components. Complexes of these antibodies and complement accumulate in the kidneys and ignite an inflammatory response.

Lupus causes various disorders of the internal structures of the kidney, including interstitial nephritis, mesangial GN, membranous GN, membranoproliferative GN, diffuse proliferative GN, and others.

It often causes nephrotic syndrome (excessive protein excretion) and may progress rapidly to renal failure. There is progressive azotemia (the accumulation of nitrogenous waste products in the blood stream) and urinary abnormalities including protein and blood in the urine.

Lupus nephritis affects approximately 3 out of 10,000 people. Systemic lupus erythematosus is most common in women, especially those 20 to 40 years old. It has a familial tendency, with a higher incidence in blacks. It may be related to other autoimmune disorders including rheumatoid arthritis and scleroderma. It has been known to be triggered by pregnancy in some cases.

In children with SLE, about 1/2 will have some form or degree of kidney involvement.